JPH044290A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain the title composition having stabilizing effects on Ac and excellent temperature characteristics to response time, comprising specific three non-chiral compounds having negative dielectric anisotropy in a specific ratio. CONSTITUTION:The objective composition comprising >=85 wt.% three components of (A) 10-25 wt.% compound shown by formula I, (B) 45-65 wt.% compound shown by formula II and (C) 10-30 wt.% one or more compounds selected from compounds shown by formula III to formula V (R<1> and R<2> are 1-18C straight-chain alkyl or alkoxy; R<3> to R<5>, R<7> and R<9> are 1-18C alkyl or alkoxy; R<6> and R<8> are 2-18C alkyl; R<10> are 2-18C alkyl or 1-18C alkoxy; l, m, n and k are 0 or 1 and l+m are 1 or 2; groups shown by formula VI to formula XII are groups shown by formula XIII to formula XV, etc.; X, Y, Z are W are F, Cl, Br or CN; * is asymmetric carbon atom).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ferroelectric liquid crystal composition, and more particularly to a ferroelectric liquid crystal composition containing a non-chiral compound having negative dielectric anisotropy. The present invention relates to a ferroelectric liquid crystal composition having dielectric anisotropy and excellent temperature characteristics of response speed, and an optical switching device using the same.

[Conventional technology]

In recent years, liquid crystal displays have come to be widely used as display elements due to their characteristics such as thinness, light weight, and low power consumption. However, most of these display elements utilize a TN display method using liquid crystal materials with a nematic phase, and the response is still slow in application fields that require high multiplexing, and there is a need for improvement. is under pressure.

In this current situation, what has been attracting attention recently is N.
This is a display method that utilizes the optical switching phenomenon of ferroelectric liquid crystals, proposed by A. Clark and S. T. Ragawal (Applied Physics Letters).
Appl, Phys, Lett, ) Volume 36, P
, 899 (1980)). Ferroelectric liquid crystal is 1
Its existence was first announced in 975 by R.B. Meyer and others (Journal de Physique).
J, de Phys,) Volume 36, P, 69 (19
(see 1975), liquid crystal classification: chiral smectic C phase, chiral smectic I phase, chiral smectic F phase, chiral smectic C phase, chiral smectic H phase, chiral smectic J phase, and chiral smectic phase (hereinafter referred to as Sc main phase, respectively). phase, S phase,
(abbreviated as SF main phase, S phase, S phase, S phase, and woody plant * G HJ * S phase).

When applying the optical switching effect of ferroelectric liquid crystal as a display element, there are two superior features compared to the TN type display system. The first feature is that it responds very quickly, and the response time is less than 1/100 compared to TN display type elements.The second feature is that it has a memory effect.
Coupled with the above-mentioned high-speed response, time-division driving is easy.

There are two possible methods for imparting memory properties to display elements using ferroelectric liquid crystals.

The first method, proposed by N., A., and Clark et al., is to create memory by unwinding the thin < L (dip) spiral by reducing the cell thickness (d) to a thickness less than the helical pitch (p). How to do it (applied physics)
Letters (Appl, Phys, Lett,) No. 3
6, P, 899 (1980)). In order to exhibit memory properties using this method, it is necessary to maintain the cell thickness at about 1 to 3 μm, since most of the current ferroelectric liquid crystal materials have a short helical pitch (1 to 3 μm). However, considering the current cell manufacturing technology, there are problems in using this method in terms of cost and yield.

The second method was discovered by Le Peasant et al.
How to create memorability using AC stabilization effect (Paris Liquid Crystal Conference
-ference, ), p. 217 (1984
).

This method is effective only for ferroelectric liquid crystal materials with negative dielectric anisotropy (Δε). The dielectric anisotropy is negative (Δε
<0) liquid crystal molecules tend to be parallel to the substrate when an electric field is applied. Switching occurs when an electric field is applied, but when a low-frequency electric field is applied, the effect of spontaneous polarization becomes dominant, and when no electric field is applied, molecules separate from the substrate, losing memory properties and reducing contrast. . However, when a high-frequency electric field is applied, the effect of spontaneous polarization cannot be followed, and the effect of dielectric anisotropy becomes dominant, and the molecules cannot separate from the substrate even when no electric field is applied, so a memory property appears and high contrast occurs. is obtained.

The AC stabilization effect utilizes the above-mentioned property when a high-frequency electric field is applied to a liquid crystal with negative dielectric anisotropy, and it can cause memory properties to appear even in thick cells (5 to 7 μm). can.

Therefore, this second method can utilize current cell manufacturing technology and is more practical than the first method.

In fact, the first time that a matrix display utilizing this AC stabilization effect was demonstrated was reported by Jarry in 1985 (SID85 Digest
P, 128 (1985)), and there have been few examples since then. The reason is that there are few ferroelectric liquid crystal materials with negative dielectric anisotropy. Also, according to the report by J.A., a voltage of approximately 40V is required to generate memory properties using the AC stabilization effect, and considering the driving voltage range of normal ICs, a much lower voltage (25V or less) is required. It is desirable that an AC stabilizing effect appear at .

The current birefringence mode type ferroelectric liquid crystal element has 5p molecules.
Due to the formation of the lay arrangement and the chevron structure, sufficient memory performance cannot be obtained, and therefore the contrast is low and it is not practical. Therefore, even with thin cells (1 to 3 μm), AC
It has become necessary to utilize a stabilizing effect, and liquid crystal materials that are compatible with this are desired.

The response time of the ferroelectric liquid crystal material reported by Schurry et al. is several -5 ec, which is still slow from a practical point of view.
In JP-A-1-306493, a ferroelectric liquid crystal composition was provided, but the temperature change in the response time was large and it was not practical. The emergence of ferroelectric liquid crystals with negative dielectric anisotropy is desired.

[Problem to be solved by the invention]

The first object of the present invention is to provide a ferroelectric liquid crystal composition that has negative dielectric anisotropy, has an AC stabilizing effect at low voltage, has high-speed response, and has excellent temperature characteristics of response time. A second object is to provide an optical switching element using the above liquid crystal composition.

[Means to solve the problem]

The ferroelectric liquid crystal composition of the present invention has at least the following AS
The ratio of the three components B and C is 10 to 25% by weight, and 45% by weight of the component B, based on the total amount of the three components A, B, and C.
~65% by weight, C component is 10~30% by weight, and the 3
It is characterized by containing 85% or more of components and having negative dielectric anisotropy.

However, component A is a compound represented by the general formula, component B is a compound represented by the general formula, component C is a compound selected from the general formula, and each component consists of one or more compounds. .

(Here, R and R2 represent the same or different linear alkyl groups or alkoxy groups having 1 to 18 carbon atoms, and R3R4R5R7 and R9 each have 1 to 18 carbon atoms.
18 same or different straight chain or branched alkyl groups or alkoxy groups, R and R8 represent straight chain or branched alkyl groups having 2 to 18 carbon atoms, and R
10 represents a straight chain or branched alkyl group having 2 to 18 carbon atoms or a straight chain or branched alkoxy group having 1 to 18 carbon atoms.

, Q, m, n and k represent 0 or 1, and 1+m represents 1 or 2.

and 0sha(Σ()(Σ(Σ and , and x, y, z and W are F and Cfi, respectively.

Indicates Br or CN; * indicates an asymmetric carbon atom. ) Component A of the liquid crystal composition of the present invention is a non-chiral compound represented by general formula (A). Since this compound has negative dielectric anisotropy and is rich in smectic C properties, it is used as the base S in the liquid crystal composition of the present invention. It plays the role of a compound (exhibiting Sc in a wide temperature range).

R1 and R2 of the compound represented by the general formula (A) of component A each represent the same or different linear alkyl group or alkoxy group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, particularly preferably is 4-10.

As a specific example of the compound represented by the general formula (A), there can be mentioned a compound represented by the formula. R1 and R
The number of carbon atoms in 2 is the same as above, and particularly preferred is 4 to 1.
It is 0. Specific R and R2 are shown in Table 1.

The compound represented by the general formula (A-1) exhibits S in a relatively high temperature range. phase and has negative dielectric anisotropy. For example, as a chiral compound represented by formula (B), a compound represented by has a phase transition temperature of Cr83.6 5c138.6 S^158.0 1
S.

The dielectric anisotropy is Δε−−7.

Component B of the liquid crystal composition of the present invention includes a chiral compound having chiral smectic C properties, in which R4 in formula (B) is an optically active group, and a non-chiral compound rich in smectic C properties.

As an example of the non-chiral compound represented by formula (B),
General formula (here, R and R14 represent the same or different straight chain alkyl groups having 1 to 18 carbon atoms, R15 represents a straight chain alkyl group or alkoxy group having 1 to 18 carbon atoms, and R16 represents an alkyl group having 2 to (16-p) carbon atoms, p represents an integer of O to 1o, and * represents an asymmetric carbon atom. Furthermore, R13 has 6 to 6 carbon atoms.
More preferably, R14 is a straight chain alkyl group having 3 to 13 carbon atoms, R15 is a straight chain alkyl group having 5 to 13 carbon atoms, and RlB is a straight chain alkyl group having 2 carbon atoms.

The above (B-3), (B-4), (B-5) and (B
Since the chiral compound represented by -6) has a small spontaneous polarization, it plays the role of the base compound of the liquid crystal composition of the present invention in the same way as the non-chiral compound. Specific R and R are shown in Tables 2 and 3, and R and R are shown in Tables 4 and 5.

Compounds represented by R13<ζ1oR14 in Table 2 (B* exhibit an S phase or an Sc phase in a relatively low temperature range and have negative dielectric anisotropy.

For example, the compound represented by C7Ht5eoc5H,1 has a phase transition temperature of Cr26.5 S 35 S 48 Sc
67.5 N68.7 IG F
s.

The dielectric anisotropy is Δε−−1.

The compound shown has a phase transition temperature Cr26. O5c46. O5A53.4 18°, and dielectric anisotropy is Δε−-2. It is also a compound that contributes to increasing spontaneous polarization and increasing the response speed of the composition.

Compounds shown as
.

It is. The dielectric anisotropy is Δε−0.5.

In addition to the above, as a compound suitable as component B, C5H
Examples include ll<奸◎-@-c2H5 C5H11(奸◎-@-C3H7 C4H9<奸◎-@-(3H7).

The C component of the liquid crystal composition of the present invention is represented by the following general formula (C-1):
Chiral (C-3) represented by ~(C-3) (where R, R and R9 each have 1 to 1 carbon atoms
8 are the same or different linear or branched alkyl groups or alkoxy groups, R and R8 are the same or different linear or branched alkyl groups each having 2 to 18 carbon atoms, and R10 is the same or different linear or branched alkyl group having 2 to 18 carbon atoms. It represents a straight chain or branched alkyl group having 18 carbon atoms or a straight chain or branched alkoxy group having 1 to 18 carbon atoms. k is 0 or W
represents F, C4), Br or CN, respectively, and * represents an asymmetric carbon atom. ) Each of R5R6R7R, R and RlO is preferably linear. Further, preferable compounds of formula (C-3) include (C-38) a) H has 5 to 12 carbon atoms, and R6 has 2 to 9 carbon atoms;
, formula (C-1) where Z is F or CN (preferably F)
a compound represented by b) H has 7 to 12 carbon atoms and R8 has 2 to 6 carbon atoms;
, where W is F or CN (preferably CN) (C-2
), C) R9 has 3 to 1 carbon atoms and R10 has 2 to 1 carbon atoms;
(C-3
Compounds represented by a) and (C-3b) can be mentioned.

Representative examples are shown in Tables 5, 6, 7 and 8.

(C-3b) can be given.

More preferable compounds of component C include the compound represented by (C-1), the compound represented by (C-3a), the compound represented by (C-2), the compound represented by (C-3b), the compound represented by a) above. is a compound described in JP-A-61-43 and JP-A-61-210056, and has large spontaneous polarization, cholesteric properties, and negative dielectric anisotropy.

For example, the compound represented by the formula has a phase transition temperature: spontaneous polarization value: 105nCcg-2 (T-Tc--10
°C), response time: 31 μsee (T-Tc--
10°C, E=5V/μm), and dielectric anisotropy Δε−-1.

The compound b) is a helical pitch adjusting agent described in Japanese Patent Application No. 63-298156 and has negative dielectric anisotropy.

For example, the compound represented by the formula has a phase transition temperature/spontaneous polarization value: 23.6 nCcm (T-Tc-10°C), a response time: 108 u See (T
Tc--10℃, E=5V/μm), dielectric anisotropy Δ
It was ε--2.

The compound C) is a compound described in Japanese Patent Application No. 103977/1982, and has large spontaneous polarization, contributing to shortening the response time. but,
Since it has positive dielectric anisotropy, if too large a quantity is used, the dielectric anisotropy of the composition may become positive, so the mixing ratio is preferably 15% by weight or less.

For example, a compound represented by a compound corresponding to formula C-3a has a phase transition temperature of 0*Cr675c96N107l8o1 spontaneous polarization value of 2327 nccm (TTc-10°C), and a response time of 45 μsec (T- Tc--10℃, E-
5V/μm).

Further, as a compound corresponding to the C-3b formula, a compound represented by has a phase transition temperature: spontaneous polarization value: 243nCcIIl (T-Tc--10
℃), response time: 30μsec (T-Tc--1
0°C, E-5V/μm).

In addition, in the compounds represented by general formulas (C-3a) and (C-3b), when the absolute configuration of the optically active site is (S, S) or (S, R) type, the polarity of spontaneous polarization is monomorphic. , and the direction of the twist of the helix is to the left. (The absolute configuration is (R,R
) or (R,S) type, each has a ten type and is on the right.

) Furthermore, the compound represented by the general formula (C-2) has the same polarity of spontaneous polarization as the compounds represented by the general formulas (C3a) and (C-3b) (the spontaneous polarizations do not cancel each other out), and has a helical polarity. Since the directions are opposite, the compound represented by the general formula (C-2) and the general formula (C-3a) or (C-3b
) The helical pitch can be lengthened by combining the compounds represented by:

The amount of component A in the composition of the present invention is 10 to 25% by weight based on the total amount of components A, B, and CB. It becomes smaller by less than 10%.

If it exceeds 25%, the viscosity becomes too high and the response speed becomes slow, and the N silks disappear and the orientation becomes poor.

Component B is 45 to 65% by weight based on the three components. 4
When it is less than 5%, the A and B components become relatively large and the viscosity becomes too high. If it exceeds 65%, the orientation becomes poor.

The amount of component C is 10 to 30% by weight based on the three components. 1
When it is less than 0%, the spontaneous polarization becomes too small and the response speed becomes slow. If it exceeds 30%, the spontaneous polarization will become too large and it will be difficult for the AC stabilizing effect to occur, and the influence of viscosity on response speed will be greater than the magnitude of spontaneous polarization, and even if the spontaneous polarization becomes large, Response speed will be slower.

Examples of the composition of the present invention other than the three components A, B, and C are as follows.

It is possible to contain it in order to achieve this or to further increase negative dielectric anisotropy. The amount in the composition is 1
Less than 5%, preferably 2-7%.

As components other than components A, B, and C, one or more compounds selected from compounds represented by the general formula are shown. Representatives of specific compounds [Examples] The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited to these examples. Various measurements in the examples were carried out using Haggi's method.

The spontaneous polarization value (P8) was measured using the Sawyer-Tauer method.
The tilt angle (θ) is determined by applying a sufficiently high electric field higher than the critical electric field to homogeneously oriented cells to eliminate the helical structure.
Furthermore, the polarity was reversed and the extinction position was determined from the shift angle (corresponding to 2θ) under crossed Nicols.

The response time was measured from the change in the intensity of transmitted light when each composition was injected into an alignment-treated cell with an electrode spacing of 2 μm and a rectangular wave with a Vp of 20 V and I KHz was applied.

Book.

The Sc hit was determined by using a homogeneously oriented cell with a cell thickness of about 200 μm and directly measuring the spacing of striped patterns (chiralization lines) corresponding to the helical pitch under a polarizing microscope.

N line pitch is determined by using a wedge-shaped cell and measuring the distance between line defects (disclination lines) (N
) was measured and indirectly determined using the theoretical formula P(pitch)-21tanθ, where θ is the inclination angle of the wedge-shaped cell.

Dielectric anisotropy is calculated by measuring the dielectric constant from the capacity of an empty cell at I KHz and the capacity when liquid crystal is injected using a cell that has been subjected to parallel alignment treatment and vertical alignment treatment. did.

(Example 1) A composition having the following composition ratio was prepared.

3% by weight of other components as component A and component B. The phase transition temperature of this composition C as the Cr-34C component is 17 nccga-2 at 25°C.
, the tilt angle is 28°, and the response time is 269 tt see
(E −5 V/μm), and the dielectric anisotropy Δε was −4.

At 40°C, the response time was 107μSee.

725°C/τ4a°C-2. 52 (τ25℃'740
The response times were 25°C and 40°C, respectively.

(Comparative example 1) A ferroelectric liquid crystal composition having the composition ratio shown below was prepared.

(The composition is a composition shown in Japanese Patent Application No. 1987-328717.) As the B component, C7H15 (Kun QC8H, 7 010H21Q effect DOCt2H25 c6a13o (8ic8H, □ 05 township) () (deceased 0B H2S 06H1be prevention trouble 8) 06H13 4.4 weight% 4.4 weight% 4.4 weight% 4.4 weight % 4.4% by weight 4.4% by weight 4.4% by weight 4.4% by weight As component C, a compound is also included as a component other than the composition of the present invention.

Amounts of B and C components The phase transition temperature of this composition d is Cr-3825℃, the spontaneous polarization value is 16 nccs-2, the tilt angle is 25℃, the response time is 340μsec (E=5V/μm), and the dielectric anisotropy Δε was −4. At 40°C, response time is 119μSeC.

The temperature was 725°C/τ -2,85.

40°C FIG. 1 shows the temperature change in response time of the composition obtained in Example 1 and the composition obtained in Comparative Example 1.

Comparing the composition of Example 1 and the composition of Comparative Example 1, the spontaneous polarization value and dielectric anisotropy are almost the same, but composition C has a shorter response time and a lower temperature at the response time. It also has excellent characteristics. Furthermore, since the composition of the present invention contains a total of 20% by weight of components B and C of the composition of the present invention, these compounds increase the viscosity and slow down the response speed. .

As is clear from the above, the composition of the present invention is A,
It can be seen that by combining the three components B and C, a ferroelectric liquid crystal composition having negative dielectric anisotropy with high-speed response and excellent response time temperature characteristics can be obtained.

(Example 2) A composition having the following composition ratio was prepared.

As component A, as component B, C3H11 (奸◎()02H5 as component C, as component A, as component B, 3% by weight. The phase transition temperature of this composition is 7% by weight of Cr-29, and the spontaneous polarization value is 17 nccs-" , the tilt angle is 2
6°, response time is 257 usee (E -5V
/μm), dielectric anisotropy is Δε−2, 100 μsec at 40”C, r25℃/τ4o℃−2,57
*, S over a wide temperature range including room temperature. A ferroelectric liquid crystal composition having a negative dielectric anisotropy with a high response time and excellent temperature characteristics of response time was obtained.

(Example 3) A composition having the following composition ratio was prepared.

5% by weight as component C. The phase transition temperature of this composition as other components is, dielectric anisotropy is Δε--2, and spontaneous polarization value is 18
ncctn, tilt angle is 25°, response time is 207μ
sec (E-5V/μm), response time of 80 μsec at 40″C, 725°C/τ −2,40, and 40°C. A composition with excellent response time and temperature characteristics was prepared.

(Example 4) Based on the present invention, a composition having the following composition ratio was prepared.

As component A, C3H17(ton0C6H13 C8HI7no C3HI7 1.5% by weight 5.8% by weight) As component C, as component B C7H154-CNoc5H, □ 1
1.2% by weight CrH15@←l0c6H138, 5% by weight C7H, 5 ((koto(Hanachi C7H1511, 6% by weight
3% by weight 2% by weight Other components The phase transition temperature of this composition is Cr-35
Book 5c66 SA 71 N 8o ISo, 25℃
, the dielectric anisotropy is -3 and the spontaneous polarization value is 18nCC.
-, tilt angle is 26°, response time is 294usec (
E-5V/um), has an S phase over a wide temperature range including response at 40"C, has a long N1 phase, has good orientation, and has a fast response, but the temperature characteristics of the response time An excellent composition was prepared.

(Example 5) The ferroelectric liquid crystal composition of Example 4 was coated with polyimide as an alignment treatment agent, and the surface was rubbed to perform parallel alignment treatment, and was applied to a cell equipped with a transparent electrode with a cell gap of 5 μm. This liquid crystal cell was placed in a crossed nicol state.
With the pulse waveform shown in Figure 2, the pulse width is 400 μsec, the peak value is 25 VI: 20 KHz, 2
When a 0V (7) AC waveform was superimposed, a good AC stabilizing effect was observed as shown in Figure 3, and a very good liquid crystal display element with good memory performance and a contrast ratio of 1:20 was obtained. .

(Example 6) The ferroelectric liquid crystal composition of Example 3 was injected into a cell equipped with a transparent electrode with a cell gap of 2 μm, coated with polyimide as an alignment agent, and subjected to parallel alignment treatment by rubbing the surface. , this liquid crystal cell is sandwiched between two polarizers arranged in a crossed Nicol state, and a pulse is generated with the bus waveform shown in Figure 2. 40
When a 20KHz, 8V AC waveform was superimposed on a 0μsec peak value of 10V, a good AC stabilization effect was observed as shown in Figure 3, and the liquid crystal element had good memory performance and a very good contrast ratio of 1:20. Obtained.

〔Effect of the invention〕

The liquid crystal composition of the present invention has negative dielectric anisotropy, good AC stabilizing effect, and excellent temperature characteristics of response time.

Furthermore, the optical switching device using the liquid crystal composition of the present invention has high-speed response and can be applied to high multiplex, liquid crystal displays, and the like.

[Brief explanation of the drawing]

FIG. 1 shows the temperature change in response time of the composition of the present invention of Example 1 and the liquid crystal composition of Comparative Example 1. FIG. 2 shows the applied voltage waveform of the composition of the present invention, and FIG. 3 is a diagram showing the optical response when an AC waveform at 25KH2 is superimposed on the voltage waveform shown in FIG. 2.

Claims (1)

[Claims] 1. At least the ratio of the following three components A, B, and C is 10 to 10% of the total amount of the three components A, B, and C.
25% by weight, 45 to 65% by weight of B component, 10% of C component
-30% by weight, and a ferroelectric liquid crystal composition having negative dielectric anisotropy and containing 85% or more of these three components. However, component A is a compound represented by the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (A), component B is a compound represented by the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B), The C component is a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (C-1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (C-2) and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (C-3 ), and each component consists of one or more compounds. (Here, R^1 and R^2 represent the same or different straight chain alkyl groups or alkoxy groups having 1 to 18 carbon atoms, and R^3, R^4, R^5, R^7 and R^
9 each represents the same or different straight chain or branched alkyl group or alkoxy group having 1 to 18 carbon atoms, and R^6 and R^8 represent a straight chain or branched alkyl group having 2 to 18 carbon atoms. , R^1^0 has 2 to 1 carbon atoms
8 linear or branched alkyl groups or 1 to 1 carbon atoms
8 represents a straight chain or branched alkoxy group. l, m, n and k represent 0 or 1, l+m is 1
Or 2. ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ are each independently ▲ Mathematical formulas There are , chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas,
There are chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Indicates X, Y, Z
and W each represent F, Cl, Br or CN, * represents an asymmetric carbon atom. 2. The liquid crystal composition according to claim 1, wherein the component A is one or more compounds selected from the following general formula (A-1): 3. B component is a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B-1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B-2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B- 3) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B-4) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B-5) and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B-6) (Thisゝ, R^1^3 and R^1^4 have 1 to 1 carbon atoms
8 same or different straight chain alkyl groups, R
^1^5 represents a linear alkyl group or alkoxy group having 1 to 18 carbon atoms, and R^1^6 represents a straight chain alkyl group or alkoxy group having 2 to 18 carbon atoms.
) represents an alkyl group. p indicates an integer from 0 to 10, *
indicates an asymmetric carbon atom. 2. The liquid crystal composition according to claim 1, comprising one or two compounds selected from the compounds represented by the following formulas. 4. The compound represented by the formula (C-3) is selected from the following: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (C-3a) and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (C-3b) 2. The liquid crystal composition according to claim 1, which is one or more kinds of compounds. 5. One or more compounds selected from the general formulas ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (D-1) and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (D-2) The liquid crystal composition according to any one of claims 1, 2, 3 and 4, containing less than 15% of the compound. (Here, R^1^7, R^1^8, R^1^9 and R^2^0 represent the same or different alkyl groups having 3 to 15 carbon atoms.) 6. Claim 1 An optical switching device characterized by using the liquid crystal composition described above.